Recently, a dicing die bonding tape has been developed, which has functions of a dicing tape adopted to fix a semiconductor wafer thereon in a dicing step where the semiconductor wafer is cut into individual chips, and a die bonding film (a die attach film) adopted to attach the semiconductor chip to a lead frame or a package substrate, or to stack the semiconductor chip in a stack package.
The dicing die bonding tape is pre-cut in consideration of workability such as attachment to a semiconductor wafer, attachment to a ring frame in a dicing process, and the like.
An example of the pre-cut dicing die bonding tape is shown in FIG. 8 and FIGS. 9(a) and 9(b). FIG. 8 shows a conventional dicing die bonding tape wound in a roll shape, FIG. 9(a) is a plan view showing the conventional dicing die bonding tape, and FIG. 9(b) is a sectional view taken along the line B-B of FIG. 9(a). As shown, the conventional dicing die bonding tape 50 includes a release film 51, an adhesive layer 52, and a pressure-sensitive adhesive film 53. The adhesive layer 52 is formed in a round shape corresponding to a shape of a semiconductor wafer, and has a round label shape. The pressure-sensitive adhesive film 53 is formed by removing a surrounding area of a round portion corresponding to a shape of a ring frame for dicing. As shown, the pressure-sensitive adhesive film 53 includes a round label portion 53a and a surrounding portion 53b surrounding an outside edge of the round label portion 53a. The adhesive layer 52 and the round label portion 53a of the pressure-sensitive adhesive film 53 are stacked on each other, while centers thereof are aligned. Further, the round label portion 53a of the pressure-sensitive adhesive film 53 covers the adhesive layer 52 and contacts with the release film 51 on a surrounding thereof.
In the dicing step of the semiconductor wafer, the release film 51 is peeled off from the stack of the adhesive layer 52 and the pressure-sensitive adhesive film 53. As shown in FIG. 10, an underside of the semiconductor wafer W is attached on the adhesive layer 52, and a dicing ring frame R is fixedly attached on the surrounding periphery of the round label portion 53a of the pressure-sensitive adhesive film 53. In this state, the dicing of the semiconductor wafer W is carried out. Afterward, the pressure-sensitive adhesive film 53 is cured through ultraviolet irradiation. Then, the semiconductor chips are picked up. At this time, since an adhesive force of the pressure-sensitive adhesive film 53 is decreased by the curing treatment, the pressure-sensitive adhesive film 53 is easily peeled off from the adhesive layer 52, and the semiconductor chip is picked up in a state that the underside thereof is attached to the adhesive layer 52. The adhesive layer 52 attached to the underside of the semiconductor chip serves as a die bonding film when the semiconductor chip is attached to the lead frame, the package substrate, or another semiconductor chip.
As shown in FIGS. 8, 9(a) and 9(b), in the conventional dicing die boding tape 50, an area where the adhesive layer 52 and the round label portion 53a of the pressure-sensitive adhesive film 53 are stacked on each other is thicker than the surrounding portion 53b of the pressure-sensitive adhesive film 53. Thus, when the conventional dicing die bonding tape 50 is wound in a roll shape as a product, the area where the adhesive layer 52 and the round label portion 53a of the pressure-sensitive adhesive film 53 are stacked on each other and the surrounding portion 53b of the pressure-sensitive adhesive film 53 are placed on top of each other, thereby causing a step between the two different areas to be transferred on the soft surface of the adhesive layer 52, that is, a transfer mark (e.g., label marks, wrinkles, or winding marks) as shown in FIG. 11. The formation of the transfer marks is remarkably increased especially when the adhesive layer 52 is formed of a soft resin and has a relatively large thickness or the dicing die bonding tape 50 is wound in a large number of times. When the transfer marks are formed, an adhesion defect occurs between the adhesive layer 52 and the semiconductor wafer, thereby causing a problem in the semiconductor wafer process.
To suppress the formation of the transfer marks, a substantially low pressure is applied when the dicing die bonding tape is wound. In this case, a winding shift may occur in a product. Accordingly, it is difficult to set the product on a tape mounter, thereby causing a trouble in an actual use of the tape.
To suppress the formation of the label marks, Patent Reference 1 discloses an adhesive sheet with a support layer disposed outside an adhesive layer and a pressure-sensitive adhesive film on a peeled base material. The support layer has a thickness equal to or larger than a total thickness of the adhesive layer and the pressure-sensitive adhesive film. According to Patent Reference 1, with the support layer, a winding pressure applied to the adhesive sheet is distributed or concentrated on the support layer, thereby desirably prohibiting a step between an area where the adhesive layer and the pressure-sensitive adhesive film are stacked on each other and an area where only the pressure-sensitive adhesive film is formed from being transferred to another adhesive layer.
According to the adhesive sheet disclosed in Patent Reference 1, the support layer is formed on the area of the peeled substrate except the adhesive layer and the pressure-sensitive adhesive film required for the manufacturing of the semiconductor device. Accordingly, the support layer has a limited width, and a relatively narrow width relative to outer diameters of the adhesive layer and the pressure-sensitive adhesive film, thereby making it difficult to suppress the transfer marks.
To effectively suppress the transfer marks, Patent Reference 2 discloses a laminating sheet used for laying a cover sheet on a light-receiving surface of an optical disc. In the laminating sheet, an adhesive sheet and a protecting material (support member) are laminated at different positions on a peeling sheet with a relatively long length. The protecting material is formed at both side portions of an underside of the peeling sheet in a width direction thereof (see FIG. 11 in Patent Reference 2). According to the structure wherein the support member is formed on the underside, the support member has a width in a wide range, thereby effectively suppressing the transfer marks.
Patent Reference 1: Japanese Patent Laid-Open Publication No. 2007-2173
Patent Reference 2: Japanese Patent Laid-Open Publication No. 2004-35836